Merge tag 'v2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

[mv-sheeva.git] / drivers / cdrom / cdrom.c

diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index af13c62dc473a1f5f8dd47b9a33b598c425477dc..e2c48a7eccffe72aafe1812fb38cde294875a1a3 100644 (file)
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -409,7 +409,8 @@ int register_cdrom(struct cdrom_device_info *cdi)
        }
 
        ENSURE(drive_status, CDC_DRIVE_STATUS );
-       ENSURE(media_changed, CDC_MEDIA_CHANGED);
+       if (cdo->check_events == NULL && cdo->media_changed == NULL)
+               *change_capability = ~(CDC_MEDIA_CHANGED | CDC_SELECT_DISC);
        ENSURE(tray_move, CDC_CLOSE_TRAY | CDC_OPEN_TRAY);
        ENSURE(lock_door, CDC_LOCK);
        ENSURE(select_speed, CDC_SELECT_SPEED);
@@ -1348,7 +1349,10 @@ static int cdrom_select_disc(struct cdrom_device_info *cdi, int slot)
        if (!CDROM_CAN(CDC_SELECT_DISC))
                return -EDRIVE_CANT_DO_THIS;
 
-       (void) cdi->ops->media_changed(cdi, slot);
+       if (cdi->ops->check_events)
+               cdi->ops->check_events(cdi, 0, slot);
+       else
+               cdi->ops->media_changed(cdi, slot);
 
        if (slot == CDSL_NONE) {
                /* set media changed bits, on both queues */
@@ -1392,6 +1396,42 @@ static int cdrom_select_disc(struct cdrom_device_info *cdi, int slot)
        return slot;
 }
 
+/*
+ * As cdrom implements an extra ioctl consumer for media changed
+ * event, it needs to buffer ->check_events() output, such that event
+ * is not lost for both the usual VFS and ioctl paths.
+ * cdi->{vfs|ioctl}_events are used to buffer pending events for each
+ * path.
+ *
+ * XXX: Locking is non-existent.  cdi->ops->check_events() can be
+ * called in parallel and buffering fields are accessed without any
+ * exclusion.  The original media_changed code had the same problem.
+ * It might be better to simply deprecate CDROM_MEDIA_CHANGED ioctl
+ * and remove this cruft altogether.  It doesn't have much usefulness
+ * at this point.
+ */
+static void cdrom_update_events(struct cdrom_device_info *cdi,
+                               unsigned int clearing)
+{
+       unsigned int events;
+
+       events = cdi->ops->check_events(cdi, clearing, CDSL_CURRENT);
+       cdi->vfs_events |= events;
+       cdi->ioctl_events |= events;
+}
+
+unsigned int cdrom_check_events(struct cdrom_device_info *cdi,
+                               unsigned int clearing)
+{
+       unsigned int events;
+
+       cdrom_update_events(cdi, clearing);
+       events = cdi->vfs_events;
+       cdi->vfs_events = 0;
+       return events;
+}
+EXPORT_SYMBOL(cdrom_check_events);
+
 /* We want to make media_changed accessible to the user through an
  * ioctl. The main problem now is that we must double-buffer the
  * low-level implementation, to assure that the VFS and the user both
@@ -1403,15 +1443,26 @@ int media_changed(struct cdrom_device_info *cdi, int queue)
 {
        unsigned int mask = (1 << (queue & 1));
        int ret = !!(cdi->mc_flags & mask);
+       bool changed;
 
        if (!CDROM_CAN(CDC_MEDIA_CHANGED))
-           return ret;
+               return ret;
+
        /* changed since last call? */
-       if (cdi->ops->media_changed(cdi, CDSL_CURRENT)) {
+       if (cdi->ops->check_events) {
+               BUG_ON(!queue); /* shouldn't be called from VFS path */
+               cdrom_update_events(cdi, DISK_EVENT_MEDIA_CHANGE);
+               changed = cdi->ioctl_events & DISK_EVENT_MEDIA_CHANGE;
+               cdi->ioctl_events = 0;
+       } else
+               changed = cdi->ops->media_changed(cdi, CDSL_CURRENT);
+
+       if (changed) {
                cdi->mc_flags = 0x3;    /* set bit on both queues */
                ret |= 1;
                cdi->media_written = 0;
        }
+
        cdi->mc_flags &= ~mask;         /* clear bit */
        return ret;
 }